Britain's half-war against Libya is careering onward from reckless gesture to full-scale fiasco. As it reaches six months' duration, every sensibly pessimistic forecast has turned out true and every jingoistic boast false. Even if the desperate and probably illegal tactic of trying to assassinate Colonel Gaddafi gets lucky, Britain would find itself running a shambles of its own making, with troops having to go in to "keep the peace". Unlike in Basra or Helmand, there will be no Americans on hand to bail them out. It is frightening how deep the imperial gene runs in generations of British politicians.

The Libyan rebels, portrayed by Whitehall propagandists as plucky little democrats, are hardly more sympathetic than Gaddafi's supporters, with those in the east at odds both with each other and with those in the west. While Britain claims to be "protecting" the population, the latest, admittedly unreliable, estimates put the civilian toll from bombing at 1,100 dead and countless injured. Certainly hundreds must have died. The RAF is clearly running out of targets and must justify each new attack in terms more appropriate to a Maoist hysteric. Last week the Tripoli television station was destroyed and reporters killed, "to disrupt the broadcast of Gaddafi's murderous rhetoric". What has that to do with the original war aim?

There remains no sign that the terror bombing of civilian areas now is contributing to military victory any more effectively than when Bomber Harris advocated it. The enterprise has been delegated to the navy and air force, each desperate to show its latest kit can be of use. They have duly deployed costly cruise missiles and Typhoon bombers, which have done no more than impose stalemate on a distant civil war at a cost of hundreds of millions of pounds.

Had David Cameron the courage of his convictions at the start and declared proper war on Gaddafi, we might be contemplating a Libyan spring. Why should we worry about Arab consent or UN support when we have had so little compunction about exceeding the Libyan mandate? The iron law of plunging into someone else's civil war is choose the side most likely to win and make sure it does. The Libyan imbroglio was a spur-of-the-moment intervention against which every red light should have been flashing when the only other country to think it a good idea was France.

Nicolas Sarkozy, like Cameron, was a leader under domestic pressure and craving a foreign policy coup. At a time when the war in Afghanistan was wretched, Libya seemed a quick win. Gaddafi was intent on doing to Benghazi what President Assad has been doing to his rebels in Syria. With the humanitarian juices running strong, and America a suddenly timid policeman, London was tempted with a precious moment of glory. The inner cabal of Cameron, George Osborne and Michael Gove reportedly saw Libya as a neoconservative epiphany. It would be like Thatcher's Falklands task force, a moment when politics aspires to statecraft and puts on the armour of crusade. The Downing Street sofa went electric.

These were men who had never gone to war and never known what war requires of government. Sound advice is drowned by a tide of patriotism. Wisdom is derided as weakness. I doubt if any of those who got Britain into this mess had the foggiest idea how they would get out of it, with Gaddafi dead or alive. Yet ahead they charged. They now have ears only for reports of imminent victory from the front, and from an intelligence service whose susceptibility to political pressure has been revealed by the Chilcot inquiry.

The serious question is why in all this did the normal checks and balances fail to operate. Where were the soldiers, diplomats and civil servants who knew Libya well, who knew about military intervention and the likely outcome of specific operations? Where was the scepticism due to any project so implausible as a "no-fly zone to impede the advance of government forces", when this did not embrace ground action (other by bombing) or a legal entitlement to remove a foreign regime? Where were the law officers or the crown? Where was the adviser to say to Cameron, you may want to do this but it must be all or nothing?

When the army wanted no part of the operation, Cameron should have smelled a rat. By assigning Libya to airmen and sailors, Cameron put in the driving seat the two services without an ounce of strategic sense. His diplomats were equally silent, sidelined by technology and a decade of failed western policy towards the Arab world. The foreign secretary, William Hague, is known to have shared Washington's scepticism of going to war in Libya. But scepticism is not enough in these matters.

Above all, where was the senior civil service, supposed constraint on unwise government? Libya is one of many items on the coalition agenda where rash politics has run ahead of common sense, like attempted reforms to government forests, tuition fees, housing benefit, court sentences and planning law. During the Thatcher and Blair eras Whitehall lost its self-confidence in curbing and channelling power. Its elite was gradually supplanted by political advisers, computer salesmen, management consultants and temporary appointments.

Whatever may have been the shortcomings of the civil service at the end of the 20th century, it was minor compared with the chaotic policy formation that took its place. From poll tax and Iraq to the NHS and Libya, the march of folly through British government seems unstoppable. Now each night a pilot flies over Tripoli and drops bombs on it, achieving nothing but death and destruction. Libya is not a dependency of the United Kingdom. It was and is no threat to Britain or its people, and the consequent rise in the price of oil is not in Britain's interest. Libya is in the grip of a wretched civil war that Britain might have relieved with aid, but not bombers. It is a mistake. But who will say so?

Parliament, silent and feeble over interventions in Afghanistan and Iraq, has spent three weeks beating its chest over the Murdoch press, even summoning the prime minister back from abroad to answer for his actions. It never summoned him over Libya, where every night people die. Parliament fiddles while Libya burns.